jQuery UI provides abstractions for low-level interaction and animation, advanced effects and high-level, themeable widgets, built on top of the jQuery JavaScript Library, that you can use to build highly interactive web applications.

JQuery is a fast, concise, JavaScript Library that simplifies how you traverse HTML documents, handle events, perform animations, and add Ajax interactions to your web pages. jQuery is designed to change the way that you write JavaScript.

The website claims XHTML Transitional status. XHTML 1.0 Transitional is the same as HTML 4.01 Transitional, but follows XML syntax rules. It supports everything found in XHTML 1.0 Strict, but also permits the use of a number of elements and attributes that are judged presentational, in order to ease the transition from HTML 3.2 and earlier. These include center, u, strike, and applet.